The Exact Time Rendering functionality increases readability of
the scheduled appointment's sequence by rendering it at its exact Start and End time corresponding with the timeslots around.
Please, uncheck the 'Enable Exact Time Rendering' checkbox, positioned just below and you will instantly get the difference that it makes.

For example:

Having appointment starting at 9:00am and finishing at 9:30am (if 9:00am is the beginning of a time slot), was
rendered the same as appointment starting at 9:25am and finishing
at 9:26am.

Exact Time Rendering can be enabled on the server through the EnableExactTimeRendering
property of RadScheduler.